It is priorly known to provide a conduction path between two contact locations of which one is movable on a circular path, while the other is disposed stationary outside such circular path. Such conduction paths have been used in the circuitry of impact protection mechanisms including safety impact bags stored in the steering columns of motor vehicles. Upon serious impact of any such motor vehicle, there is the requirement that the safety impact bag be instantaneously expelled from the steering column and inflated by the provision of high pressure gas. Each of such mechanisms has included a source of high pressure gas coupled to the safety impact bag, and an igniter circuit that activated such source in response to control signals from an on-board vehicle computer. The transmission of such control signals required a conduction path between the aforesaid stationary contact location and the rotatable contact location mounted in the steering wheel, the latter of which required an ability to be rotated up to six revolutions with the steering wheel.
In the prior mechanisms such conductive path comprised a coiled spring formed of a metal band positioned about the rotatable contact location. Upon the rotation of the rotatable contact location in one direction, the windings of such coiled spring were pulled together to reduce the diameter of the spring; while rotation in the opposite direction caused the windings of such coiled spring to expand and increase the diameter of the spring. Accordingly, the relative movement of the two contact locations connected by such coiled spring resulted in a "breathing" motion, similar to a watch spring. To enable the rotatable contact location to rotate at least six revolutions, the coiled spring of the prior art required a large number of windings and, consequently, the metal band of which it was comprised had an extensive length. As the electrical resistance of the metal band was directly proportional to its length, such length was an impediment to the transmission of the control signals to the igniter circuit.